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Nutritional supplement boosts productivity—for plants

Nature is full of organisms from different species that work together to survive. The best-known example might be the Egyptian plover – the tiny bird that’s famous for picking food out of the Nile crocodile’s teeth. If you think it’s crazy for a 50-gram bird to venture into a crocodile’s mouth, think of it this way: the plover lands an easy meal, and the croc tolerates the bird (instead of snacking on it) in exchange for a free dental cleaning. In a situation like this one – a symbiosis – everybody wins.

Don Smith, a researcher in McGill’s Faculty of Agricultural and Environmental Sciences, is on the front lines of the worldwide fight to find clean green ways of feeding burgeoning populations. He’s studying a symbiosis too, except that this one involves legumes (like soybeans, peas and lentils) and certain kinds of bacteria that live in their roots.

“The bacteria take nitrogen out of the atmosphere,” Smith says, “and they give it to the plants as a nutrient, which means they can grow without nitrogen fertilizer. The plants also produce compounds that the bacteria need to start the symbiosis. The plants and bacteria send signal compounds back and forth – a little like a molecular chitchat, or password exchange. It turns out that the microbe-to-plant signals also directly stimulate plant growth – and not just in legumes, but in a lot of plants.”

But cold climates (like Canada’s) and other factors can get in the way, preventing the plants and bacteria from talking to each other. The result is smaller plants, leaner crops, and less food to go around. To solve the problem, Smith and his team decided to cultivate the bacteria’s chemical “password” themselves, and distribute it as a plant supplement.

“The plant-to-microbe signals were already available on the market,” Smith says, “but the microbe-to-plant signals weren’t, and they were needed to stimulate growth. We patented all this, and this coming season they’ll be available in Canada.”

Farmers who use the new supplement can expect about a five per cent increase in their crop yields, at a cost of just a few pennies per hectare. If five per cent doesn’t sound like much, consider this: in a year, about 212 million metric tons of soybeans are grown around the world. A five per cent increase would mean some 10.6 million extra tons.

The supplement also reduces the need for nitrogen fertilizers, which release greenhouse gases into the air. “Whenever you lay down nitrogen fertilizer,” Smith says, “one or two per cent goes off into the atmosphere as nitrous oxide – a very powerful greenhouse gas that captures heat 310 times more effectively than carbon dioxide.”